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To elucidate the mechanisms of Zr + reacting with COS,both the quartet and doublet potential energy surfaces (PESs) for reactions of Zr + (4 F,2 D) with COS in the gas phase have been investigated in detail by means of density functional method (B3LYP).To obtain more accurate results,the coupled cluster single-point calculations (CCSD(T)) using B3LYP optimized geometries were performed.For the C-O bond activation,the calculated results indicate that both the quartet and doublet states proceed via an insertion-elimination mechanism.For the C-S bond activation,the quartet reaction has an insertion-elimination mechanism,but the doublet reaction is a direct abstraction of the sulfur atom by Zr +.The C-S bond activation is found to be energetically more favorable than the C-O bond activation.It is found that the reaction of the 4 F gound state of Zr + to yield ZrO + is spin-forbidden (Zr + (4 F) + COS (1 Σ) → ZrO + (2) + CS (1 Σ)) and the crossing points were approximately determined.All the results have been compared with the existing experimental and theoretical data. 相似文献
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应用密度泛函理论BHandH/6-31G**计算方法研究新型手性非金属催化剂1,3,2-噁唑磷烷-硼烷催化还原苯乙酮的对映选择性反应机理, 确定了在反应途径上的反应物、络合物、过渡态, 中间体和对映体中间产物. 计算结果表明, 该对映选择性还原反应是两个平行的分步反应, 对映体产物主要是(R)构型. 采用同样的方法研究了对映选择性还原反应在甲苯中的溶剂化效应. SCRF计算显示, 甲苯溶剂不改变反应的机理, 但能降低各驻点的能量和(R)反应的位垒, 有利于催化还原反应朝生成(R)构型中间产物的方向进行. 相似文献
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The reaction mechanisms of carcinogenic methylating agent iodomethane (MeI) with keto and enol tautomers of thymine (K- and E-thymine) were studied by using the B3LYP/6-311+G (d, p) method in water phase. The solvent effects were examined using the polarizable continuum model (PCM). Specifically, PCM single-point calculations at the same level of theory were performed in acetone and CCl4 that represent a range in nonpolarity. The calculated results show that the reaction of K-thymine with MeI is a two-step mechanism, whereas that of E-thymine is a one-step mechanism. Our calculations reveal that K-thymine is appreciably more stable than the enol form in the water phase or in the two solvents. The K- and E-form reaction barriers are 135.6 and 222.1 kJ/mol, respectively in water phase. These findings indicate that the reactions mentioned above could not occur efficiently in biological media in the absence of catalyst. Our conclusions are in agreement with the previous studies on the reactions of guanine with methyl chloride and methyl bromide. 相似文献
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二安替比林对碘苯基甲烷与铬(Ⅵ)显色光度法研究 总被引:4,自引:0,他引:4
本文研究了在 Mn( )存在下新试剂二安替比林对碘苯基甲烷 (DAp IM)与 Cr( )反应生成桔红色配合物 ,λmax为 4 88nm,表观摩尔吸收系数 ε=2 .0 5× 10 5L.mol-1.cm-1,Cr( )含量在 0— 8.0 μg/ 2 5 m L范围内符合比耳定律 ,线性回归方程为 A=0 .0 2 65 +0 .141C(μg/ 2 5 m L) ,r=0 .9974 ,方法用于电镀废水中铬的测定 ,结果令人满意 相似文献
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The reactions of Mn+(7S,5S) with CS2 have been studied at the B3LYP/TZVP level on both septuplet and quintet potential energy surfaces(PESs).The overall energies have been refined at the CCSD(T) level.The calculated results indicate that the reactions of Mn+(7S,5S) with CS2 proceed via an insertion-elimination mechanism.Calculations show that the quintet reaction is more favorable than the septuplet under high energy conditions.The spin-forbidden reaction Mn+(7S) + CS2 → MnS+(5Π) + CS proceeds through a septuplet-quintet surface and the crossing seam is approximately determined.All results have been compared with the existing experimental and theoretical data. 相似文献
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取代基对手性唑噁唑硼烷催化还原苯基乙基酮对映体选择性影响的理论研究 总被引:3,自引:0,他引:3
用AM1方法和过渡态理论研究了取代基对含侧链手性噁唑硼烷催化还原苯 基乙杂程逖≡裥缘挠跋欤扑憬峁砻鳎杂逞≡裥匀【鲇?R)和(S)两个对映体?
叫蟹从Φ乃俾食J龋盋(4)和C(5)位上的取代基呈顺式时,所得对映体以(R) 型为主.对映选择性的高低与噁唑硼烷环上不同位置原子连接的取代基基团的大?
∮泄兀扑憬峁胧笛樽芙岢龅慕崧巯辔呛希?
$601 $AThe influence of substituents on the enantioselectivity in asymmetric branched-oxazaborolidine-catalyzed reductions of phenyl- ethyl ketone has been studied by using AMI MO method and transition state theory. The results show that the enantioselectivity is determined by the ratio of the rate constants of two parallel reactions conducting to spatial configurations (R) and (S). When the substituents connecting with C(4) and C(5) are in cis-form the reduction products of phenyl-ethyl ketone in the reactions are mainly of configuration ( R). In asymmetric boron-catalyzed reduction reactions the higher or lower magnitude for enantioselectivity and reaction barrier are governed by various substituents connecting with atoms of oxazaborolidine ring. The computational results are in consistence with experiments. 相似文献
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用DFT方法研究了氮杂炔正离子[R-C≡N-CH3] 与二环[2,2,1]-2-庚烯的反应机理。所有几何构型用B3LYP/6-31G**基组进行优化,过渡态通过振动分析和内聚反应坐标进行了确认。并在相同基组上研究了当R为不同取代基时的反应变化规律。结果表明该反应为环加成反应,有两条反应途径,产物主要通过能量较低的过渡态TSa生成。当取代基为支链烷烃基团时,反应位垒较大;取代基为直链烷烃基团和苯环时,反应较易进行。 相似文献
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用过渡态理论和AM1方法,对8-二甲基-7-甲氧基-5-烯-壬腈氧化物分子内环加成反应机理进行了研究。结果表明,存在两种产物的平行反应,对两个反应的速率常数比值的计算,得到反式和顺式的产率比为90.5:9.5,与实验产率比值(≥85:15)结果接近。标题物立体专一选择性由活化焓和活化熵共同决定。 相似文献